A semiconductor light source such as LED is a light source and a display device produced by a third generation semiconductor material with lower power consumption, long lifespan, no pollution, rich colors, high controllability and other characteristics, which is a revolution in lighting sources and lighting industry. With development of LED, there are more and more LED lighting products in the market. An electronic driving portion for LED is an indispensable component in a LED lighting product.
From a viewpoint of the LED market, a LED lighting device still has a higher price than a traditional light bulb or an energy saving lamp, and how to reduce the price of a LED lighting device has become a key-point of improving market acceptance.
With descending of price of a LED unit, the price of the electronic driving portion plays a more important role in the total price of a LED lighting product. Currently, most of the LED driving circuits popularly used in the market adopt an IC controller, the main drawback of which is a higher price. If the IC controller is not adopted, a fly-back self-excited oscillation circuit is usually adopted, but such circuit has a low efficiency and a poor stability and only can output a narrow range of voltage.